Studies On Local Structures Of Materials Using Aberration Corrected Transmission Electron Microscope And First Principles Calculations

The microstructures of materials have multi-scale characteristics.In view of micro/nano scale situations,the structures and properties of local areas in materials like surfaces,interfaces and dislocations,often have a significant difference with that of bulk and have great influence on the properties and applications of the whole material.In order to stay closer to the practical application,our studies on materials have been gradually changed from single crystal bulk materials to local areas in materials.With the rapid development of nanotechnology,we've been able to synthesize a variety of micro/nano materials with complex structures,greatly enriched the research objects of material science.In the past,direct characterization methods focused on the local structure of materials were very limited,what's more,the limitation of the resolution made people hard to obtain accurate local structure information of materials.In recent years,the analysis and characterization technology for materials have been greatly enhanced,especially,the appearance and development of aberration corrected high resolution transmission electron microscopy?Cs-corrected HRTEM?made us be able to directly observe the local structures of materials,obtain micro/nano scale even atomic scale structural information and achieve unprecedented data and conclusions,which are of great significance and promotion for the application and development of functional materials.On the other hand,the development of computational materials science and hardware platform make it realizable to deal with the local structure that much closer to the practical situation.By taking advantage of the aberration corrected high resolution electron microscopy,we studied zero dimension,one-dimensional,two-dimensional and three-dimensional local structures in several typical functional materials and achieved a series of structure data.At the same time,first-principles calculations based on density functional theory were conducted to deeply investigate the atomic configuration and electronic property of the local areas in these materials.Furthermore,we discussed the relationship between the local structures and properties of these materials.These works provide considerable supplements of the understanding on the structures and properties of these materials.Following are several main conclusions of this thesis:We successfully synthesized hexagonal-closed packed rhodium,characterized the atomic structure and elaborated the size-dependent formation mechanism of it.The non-stoichiometric dislocation core in wurtzite ZnO was deeply studied using exit-wave reconstruction technology and first-principles calculations,and the partial occupy and atomic configuration of redundant Zn atoms in the core area were confirmed.We precisely characterized the atomic structures of CeO₂{100},{110}and{111}surfaces,making a supplementary for the researches on CeO₂ surface structures.Surface engineering on the rutile TiO₂submicron particles significantly improved the overall electrochemical performance of rutile TiO₂ particles as an anode material in lithium ion batteries.Three dimensional reconstruction technology was used to overcome the difficulty on the characterization of MOF@Frame system.